Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 09/30/23

Area Forecast Discussion

National Weather Service Grand Rapids MI

 1058 PM EDT Fri Sep 29 2023

LATEST UPDATE...
Update

.UPDATE...
Issued at 1058 PM EDT Fri Sep 29 2023

Visibilities of 1/2 mile or less are already showing up on some
of the area observations. Given the earlier widespread clearing
and now the presence of dense fog patches already before midnight,
have issued a Dense Fog Advisory through 10 AM Saturday morning.
Have excluded the lakeshore counties from MKG northward for now
where model vsby guidance is less bullish.

UPDATE Issued at 852 PM EDT Fri Sep 29 2023

A large part of the area has already cleared out, with the
exception of the U.S. 127 and U.S. 10 corridors. The current
extent of clearing means that the radiation fog threat has
increased. We should see some locally dense patches forming
overnight with calm winds and dew points still around 60.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 317 PM EDT Fri Sep 29 2023

Widespread cloud cover is in place across lower Michigan this
afternoon associated with a combination of low stratus associated
with low- level moisture across the area and cumulus that formed
in pockets of stratus breaks. High resolution model guidance
currently suggests that these clouds will decrease tonight into
the overnight hours.

The decreasing cloud cover scenario sets the stage for the
potential of areas of fog across the area near daybreak Saturday.
ACARS soundings at Grand Rapids airport show ample low-level
moisture trapped under an inversion around 850 mb and light winds.
Model soundings suggest this will continue through the night
leading to the potential for fog, mainly near and east of US131.
The most favored region for fog at this point looks to be near
US127, particularly near Jackson where visibilities are forecast
to dip as low as 0.5-1 miles. One caveat is that if the low-level
stratus can hang on for longer than anticipated this would inhibit
radiational cooling and by extension fog formation. However,
clearing skies and fog is the current favored solution.

Outside of the fog potential, benign weather is expected across
lower Michigan through the short term period as ridging moves into
place across lower Michigan, associated with an omega block pattern
forming across the CONUS. Cloud cover Saturday is not anticipated to
be as thick as today with mainly some cumulus possible. 850 mb
temperatures in the teens Celsius looks to support highs on
Saturday to reach the mid to upper-seventies.

.LONG TERM...(Sunday through Friday)
Issued at 317 PM EDT Fri Sep 29 2023

High pressure continues with highs in the upper 70s to low 80s and
overnight lows in the mainly in the 50s. There is high
confidence in these above normal temperatures as seen by
the different model solutions. Ensembles also highlight
precipitation toward the second half of the work week when a trough
moves into the area. Southwest winds pick up ahead of the
trough, bringing one last gasp of warmer temperatures before more
fall like conditions move in by the following weekend.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 630 PM EDT Fri Sep 29 2023

Conditions are expected to gradually improve from MVFR to VFR
early this evening as cigs improve and more clearing develops.
However we expect that this clearing will increase potential for
areas of fog to develop during the early morning hours Saturday.

As a result we expect conditions to deteriorate to MVFR/IFR at
most of the terminals early Saturday morning with some LIFR in
denser fog as well. Conditions will then slowly improve to VFR at
all the terminals during the mid to late morning hours as fog
gradually dissipates and cigs improve. VFR conditions are then
expected at all the terminals from midday through Saturday
evening.


&&

.MARINE...
Issued at 317 PM EDT Fri Sep 29 2023

High pressure setting up in the eastern Great Lakes region will
support a weak pressure gradient across Lake Michigan, keeping
winds light through early next week. Southerly flow sets up in
association with this high pressure system with gusts reaching
10-15 knots in the afternoon Saturday and Sunday. GFS bufkit
overview at the Lake Michigan South buoy reflects this overall
expectation. Gusts don`t look to exceed 20 knots until mid-next
week. Waves also look to remain at or below 2 feet until
Wednesday.


&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Dense Fog Advisory until 10 AM EDT Saturday for MIZ038>040-
     044>046-051-052-056>059-064>067-071>074.

LM...None.
&&

$$

UPDATE...Meade
SHORT TERM...Thomas
LONG TERM...RAH
AVIATION...Laurens
MARINE...Thomas